Free Naval Architecture & Marine Engineering Calculators

Free online calculators for naval architects, marine engineers, ship operators & maritime professionals. Calculate ship resistance, propulsion power, hull coefficients, stability, fuel consumption, EEOI, MRV CO₂ emissions & other vessel performance parameters.

Find a calculator

New Calculators

Recently added tools for emissions, stability curves, and operating efficiency.

MRV CO2 Recorder
Voyage emission logbook.
New
Record fuel use, calculate CO2 emissions, track MRV scopes, and export reports.
Open Recorder
GZ Curve Generator
Righting arm curve tools.
New
Generate and review a righting arm curve from practical stability inputs.
Open Calculator
Speed Optimization
Fuel-speed tradeoff.
New
Compare operating speed choices for fuel use, emissions, and voyage planning.
Open Calculator

Browse Calculators

Full calculator menu with category filters available from the top ribbon.

Show all calculators

Hull Design

Core hydrostatics & hull-form coefficients used in early-stage design and comparisons.

Block Coefficient (CB)
How “full” the underwater volume is.
Hull
Calculates CB from principal dimensions and displacement volume to quantify hull fullness.
Open Calculator
Midship Coefficient (CM)
Midship section “efficiency”.
Hull
Relates midship sectional area to B×T to evaluate section fullness.
Open Calculator
Prismatic Coefficient (CP)
Volume distribution along length.
Hull
Computes CP from displacement volume, L and midship area to support resistance trends.
Open Calculator
Waterplane Coefficient (CWP)
Waterplane “fullness”.
Hull
Finds CWP as AWP / (LWL × BWL), useful for stability & seakeeping intuition.
Open Calculator
Displacement
Mass/weight from volume & density.
Hull
Convert between displacement volume and mass using seawater/freshwater density.
Open Calculator
Waterplane Area (AWP)
Area at the waterline.
Hull
Estimate AWP for hydrostatics and stability calculations.
Open Calculator
Wetted Surface Area (WSA)
Skin friction driver.
Hull
Compute WSA to support frictional resistance estimates and scaling checks.
Open Calculator
LCB
Longitudinal centre of buoyancy.
Hull
Locate buoyancy centre along length to support trim/balance checks.
Open Calculator
LCF
Longitudinal centre of flotation.
Hull
Find the pivot point for small trim changes (important for trim/MCT logic).
Open Calculator
Bulbous Bow Volume & Area
Bulb geometry helpers.
Hull
Quick bulb metrics used in preliminary resistance discussions.
Open Calculator

Resistance

Estimate calm-water resistance with commonly used empirical/semi-empirical methods.

Holtrop–Mennen
Industry-standard resistance prediction.
Popular
Predict resistance components using principal dimensions and form factors.
Open Calculator
Savitsky (Planing)
Planing hull resistance approach.
Res
Trim, lift and resistance estimates for planing craft.
Open Calculator
Telfer
Alternative resistance estimator.
Res
Empirical resistance estimation method for preliminary checks.
Open Calculator
Froude Estimator
Speed-based approximation.
Res
Quick resistance estimates using ITTC friction + residual assumptions.
Open Calculator
Model–Ship Correlation
Scaling & correlation tools.
Res
Convert model data to full-scale using standard correlation practices.
Open Calculator
Speed–Power Curve
Generate a curve from assumptions.
Res
Build a speed–power relationship using resistance estimates and efficiencies.
Open Calculator

Propulsion & Power

Translate resistance into effective, delivered and brake power — and evaluate key efficiency factors.

Propeller Slip
Advance vs actual travel.
Prop
Compute slip percentage from pitch, RPM and vessel speed.
Open Calculator
Propeller Efficiency (η₀)
Open-water efficiency.
Prop
Evaluate η₀ from thrust/power relationships (as per your calculator logic).
Open Calculator
Hull Efficiency (ηH)
Wake/thrust deduction effect.
Prop
Compute hull efficiency from wake fraction and thrust deduction.
Open Calculator
Relative Rotative Efficiency (ηR)
Behind-hull prop effects.
Prop
Compare behind-hull and open-water performance.
Open Calculator
Effective Power (PE)
Power to overcome resistance.
Popular
Compute PE from resistance and speed.
Open Calculator
Delivered Power (PD)
Power at the shaft/prop.
Power
Convert effective power to delivered power using efficiency chain.
Open Calculator
Brake Power (PB)
Engine output requirement.
Power
Estimate PB from PD and drivetrain efficiencies.
Open Calculator

Stability & Load

Initial stability, trim, free surface effects, and longitudinal balance helpers.

GM
Initial transverse stability.
Stab
Evaluate GM and basic initial stability indicators.
Open Calculator
Trim
Longitudinal balance estimate.
Stab
Trim and longitudinal balance checks for loading changes.
Open Calculator
Free Surface Correction (FSC)
Slack tank stability loss.
Stab
Apply FSC to account for reduced GM due to free surface in tanks.
Open Calculator
MCT 1 cm
Moment to change trim.
Stab
Estimate MCT 1 cm for trim change calculations.
Open Calculator
GZ Curve Generator
Righting arm curve tools.
New
Generate and interpret a GZ curve based on stability inputs.
Open Calculator

Fuel & Machinery

Fuel consumption, engine efficiency, emissions, and operational performance tools.

MRV CO2 Recorder
Voyage emission logbook.
New
Record vessel fuel use, calculate CO2 emissions, track MRV scopes, and export reports.
Open Recorder
Fuel Consumption
Engine fuel usage estimate.
Fuel
Estimate fuel consumption based on power, speed, and operating time.
Open Calculator
SFOC
Specific fuel efficiency.
Fuel
Analyze specific fuel oil consumption for marine engines.
Open Calculator
Fuel Cost
Voyage cost estimation.
Fuel
Calculate total fuel costs using consumption rates and fuel prices.
Open Calculator
CO₂ Emissions
Carbon output estimate.
Fuel
Estimate CO₂ emissions based on fuel type and consumption.
Open Calculator
EEOI
Operational efficiency index.
Fuel
Evaluate Energy Efficiency Operational Indicator for voyages.
Open Calculator
Speed Optimization
Fuel–speed tradeoff.
New
Identify optimal operating speed for fuel and emission efficiency.
Open Calculator

General Utilities

Quick helpers used across engineering workflows.

Unit Converter
Engineering unit conversions.
Popular
Convert common marine/engineering units quickly and safely.
Open Calculator
Percentage
Percent change and ratios.
Gen
Compute percent difference, increase/decrease, and ratio-based outputs.
Open Calculator
Date Calculator
Add/subtract dates.
Gen
Add or subtract durations and compute date differences.
Open Calculator
Linear Interpolation
Interpolate between points.
Gen
Quick linear interpolation for tables and curves.
Open Calculator
Reynolds Number
Flow regime quick check.
Gen
Compute Reynolds number for basic hydrodynamic reasoning.
Open Calculator
Density Converter
Common density units.
Gen
Convert density between kg/m³, g/cm³ and other common units.
Open Calculator
Back to top ↑